Link does not speak. Not one text bubble is dedicated to him. When talking to villagers, they seem to read his mind and answer his questions before he asks them... So how then can we know what he is like? Does he have a sense of humor, or an accent?
He barely even interacts with his surroundings. People say some weird shit to him and all he does is stand there silently. (King Zora asking for a kiss comes to mind.)
So, instead of focusing on what he does not do (because that could take all day), let us focus on what he does do; what he does react to.
The following are times Link smiles.
§ When he catches a fish.
§ When he receives a medallion.
§ Right before the final battle, when Link and Zelda look at each other and rejoice because they think they have won...
The following are times Link expresses sadness or hesitation.
§ Leaving the forest after Saria gives him her ocarina.
§ Returning to the Sacred Forest Meadow after seven years, only to discover Saria is not there.
§ After the final battle, returning the Ocarina of Time to Zelda.
The following are times Link expresses shock.
§ When Ruto tells him they are engaged.
§ When Koume and Kotake become Twinrova.
§ When he sees that Kakariko Village is on fire.
§ Before the final battle, when a loud clang is heard.
§ Seeing Ganon's Castle for the first time.
§ When the Deku Sprout suddenly bursts from the ground. (I love that scene; he actually falls over. XD)
§ When Ganondorf sees Link spying on him in the courtyard.
§ When Ganondorf appears after Impa and Zelda escape from the castle.
§ When the Master Sword is thrown from his hand during the final battle. (and even then he doesn't seem too surprised)
§ When Ganondorf captures Zelda in the Temple of Time.
§ When he enters Ganondorf's lair and sees Zelda still imprisoned in the crystal.
§ When he wakes after seven years and discovers he has aged. ...Although it doesn't seem he really minds. Navi acted more excited.
§ Falling off of cliffs. Apparently this is very uncomfortable for Link.
§ When Sheik reveals that he is Zelda.
§ When Darunia and the other Gorons offer their new "brother" a hug and Link runs off screaming.
The following are times Link stood silently, when I think he should have reacted. >_o
§ Ganon's Tower collapsing. Zelda gets the hell outta there, while Link turns around to watch.
§ When he finds out he holds the Triforce of Courage.
§ When King Zora offers a kiss. Nightmares...
§ When Ganon slices the air just inches from Link's face.
§ When it is discovered that Nabooru is the Iron Knuckle that attacks him. ...Then he just stands there while Koume and Kotake zap her.
§ When the Poe Collector hits on him. I was scared.
§ When Darunia begins dancing crazy-insane.
Any other actions he performs during OoT.
§ When in a hot place... He rolls his eyes and sighs deeply, then wipes the sweat from his brow.
§ When in a cold place... He holds his arms and shivers, then sneezes, afterwards making a kind of "I feel sick" grunt.
§ When suffering critical damage... He bends over, resting his hands on his knees and breathes heavily.
§ Sometimes he taps his boots on the ground.
§ If his sword is out of the sheath, he will take a few swipes at the air. Then look all amazed.
§ Sometimes he adjusts his tunic.
§ If Link takes one hit too many, he falls to his knees and finally, to the floor. (i.e., Game Over)
§ If he barely reaches a ledge or begins to fall off of one, he will gasp.
§ Sometimes he takes a look over his shoulder.
§ If on his horse, he will pat her on the neck.
§ When left under water for too long, he will struggle a bit, then his arms and legs will become limp and he will float to the top. (Makes him sound like a dead gold fish, doesn't it? @_o)
§ Even with the Zora Tunic on, when Link reaches the surface of the water he takes a big breath of air.
§ If a monster attacks him while he is running, he will hold his right arm in front of his face and bend over slightly.